As the world continues to shift towards renewable energy, one of the greatest challenges we face is how to store energy for use when the sun isn't shining or the wind isn't blowing. Two promising solutions to this problem are hydrogen fuel cells and battery storage. But which technology produces less CO2 emissions?
What are Hydrogen Fuel Cells?
Hydrogen fuel cells convert hydrogen gas (H2) into electricity, producing only water and heat as by-products. They work by passing hydrogen through an anode and splitting it into protons and electrons. The electrons are then used to create electricity, while the protons combine with oxygen to produce water. This technology is emission-free at the point of use, making it a promising solution for transportation and energy storage.
What is Battery Storage?
Battery storage works by storing electrical energy in chemical form. When electricity is needed, the batteries release the stored energy back into the electrical grid. While there are various types of batteries, lithium-ion batteries are currently the most commonly used for energy storage.
CO2 emissions from Hydrogen Fuel Cells
Although hydrogen fuel cells produce only water and heat as by-products, the production of hydrogen gas requires energy. This energy can come from renewable sources such as solar and wind, but it can also come from non-renewable sources such as natural gas. The latter results in the production of CO2 emissions.
According to the Department of Energy, the well-to-wheels carbon footprint of hydrogen from natural gas is about 85 grams of CO2 per megajoule of energy produced. This means that for every megawatt-hour of electricity produced, approximately 65-100kg of CO2 emissions are produced, depending on the source of the hydrogen gas.
CO2 emissions from Battery Storage
The production of batteries also requires energy, which can come from renewable or non-renewable sources. The main greenhouse gas emissions associated with battery manufacturing are the CO2 emitted during the production of the raw materials and the energy used during manufacturing. The production of lithium-ion batteries, which are the most commonly used type for energy storage, produces approximately 70-80 kg of CO2 emissions per kilowatt-hour of storage capacity.
Hydrogen Fuel Cells vs. Battery Storage
In terms of CO2 emissions, both hydrogen fuel cells and battery storage have a carbon footprint associated with their production. However, the carbon footprint associated with hydrogen fuel cells is generally higher than that of batteries. While both technologies have the potential to be powered by renewable energy sources, it's important to note that the greenhouse gas emissions associated with their production can be a significant factor in determining their overall environmental impact.
Final Thoughts
Deciding between hydrogen fuel cells and battery storage comes down to a variety of factors, including cost, efficiency, and practicality. While both technologies have their benefits, it's important to consider their environmental impact as well. Ultimately, the best solution may be a combination of the two technologies, with hydrogen fuel cells used for specialized applications and battery storage used for more general applications.
References
- Department of Energy. (2021). Hydrogen Production: Natural Gas Reforming. Retrieved from https://www.energy.gov/eere/fuelcells/hydrogen-production-natural-gas-reforming
- Green, M. A., Emery, K., Hishikawa, Y., Warta, W., & Dunlop, E. D. (2019). Solar cell efficiency tables (Version 54). Progress in Photovoltaics: Research and Applications, 27(7), 565-575.
- Hawkins, T. R., Singh, B., Majeau-Bettez, G., & Strømman, A. H. (2012). Comparative environmental life cycle assessment of conventional and electric vehicles. Journal of Industrial Ecology, 17(1), 53-64.